The present invention relates to a treatment for glaucoma and more particular to a method and apparatus for applying an electrical field in the vicinity of the trabecular meshwork to manipulate glycosaminoglycans in the trabecular meshwork.
Glaucoma, a group of eye diseases affecting the retina and optic nerve, is one of the leading causes of blindness worldwide. Glaucoma results when the intraocular pressure (IOP) increases to pressures above normal for prolonged periods of time. IOP can increase due to an imbalance of the production of aqueous and the drainage of the aqueous. Left untreated, an elevated IOP causes irreversible damage the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision.
The eye's ciliary body constantly produces aqueous, the clear fluid that fills the anterior chamber of the eye. The aqueous flows out of the anterior chamber through a complex drainage system. The balance between the production and drainage of aqueous determines the eye's IOP.
Open angle (also called chronic open angle or primary open angle) is the most common type of glaucoma. With this type, even though the anterior structures of the eye appear normal, aqueous fluid builds within the anterior chamber, causing the IOP to become elevated. Left untreated, this may result in permanent damage of the optic nerve and retina. Eye drops are generally prescribed to lower IOP. In some cases, surgery is performed if the IOP cannot be adequately controlled with medical therapy.
Only about 10% of the glaucoma population suffers from acute angle closure glaucoma. Acute angle closure occurs because of an abnormality of the structures in the front of the eye. In most of these cases, the space between the iris and cornea is more narrow than normal, leaving a smaller channel for the aqueous to pass through. If the flow of aqueous becomes completely blocked, the IOP rises sharply, causing a sudden angle closure attack.
Secondary glaucoma occurs as a result of another disease or problem within the eye such as: inflammation, trauma, previous surgery, diabetes, tumor, and certain medications. For this type, both the glaucoma and the underlying problem must be treated.
FIG. 1 is a diagram of the front portion of an eye that helps to explain the processes of glaucoma. In FIG. 1, representations of the lens 110, cornea 120, iris 130, ciliary body 140, trabecular meshwork 150, and Schlemm's canal 160 are pictured. Anatomically, the anterior chamber of the eye includes the structures that cause glaucoma. Aqueous fluid is produced by the ciliary bodies 140 that lie beneath the iris 130 and adjacent to the lens 110 in the anterior chamber. This aqueous washes over the lens 110 and iris 130 and flows to the drainage system located in the angle of the anterior chamber. The angle of the anterior chamber, which extends circumferentially around the eye, contains structures that allow the aqueous to drain. The first structure, and the one most commonly implicated in glaucoma, is the trabecular meshwork 150. The trabecular meshwork 150 extends circumferentially around the anterior chamber in the angle. The trabecular meshwork 150 seems to act as a filter, limiting the outflow of aqueous and providing a back pressure producing the IOP. Schlemm's canal 160 is located beyond the trabecular meshwork 150. Schlemm's canal 160 has collector channels that lead to aqueous veins that allow aqueous to flow out of the anterior chamber. The two arrows in the anterior chamber of FIG. 1 show the flow of aqueous from the ciliary bodies 140, over the lens 110, over the iris 130, through the trabecular meshwork 150, and into Schlemm's canal 160 and its collector channels.
Glaucoma is treated most commonly with eye drops. When eye drops prove ineffective, surgical intervention may be necessary. Currently, there are a variety of invasive surgical procedures that are used to treat glaucoma. Most of these procedures subject the patient to an incision in the eye that can lead to complications. Accordingly, a treatment that does not involve an incision would be beneficial.
The present invention provides a method and device for applying an electric field in the vicinity of the juxtacanalicular region of the trabecular meshwork sufficient to cause the glycosaminoglycans in the extracellular matrix to migrate and/or reorient thereby reducing the resistance to aqueous outflow through the trabecular meshwork.